1 /* s_ilogbf.c -- float version of s_ilogb.c.
2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3  */
4 
5 /*
6  * ====================================================
7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8  *
9  * Developed at SunPro, a Sun Microsystems, Inc. business.
10  * Permission to use, copy, modify, and distribute this
11  * software is freely granted, provided that this notice
12  * is preserved.
13  * ====================================================
14  */
15 
16 #include "math.h"
17 #include "math_private.h"
18 
19 int
20 ilogbf(float x)
21 {
22 	int32_t hx,ix;
23 
24 	GET_FLOAT_WORD(hx,x);
25 	hx &= 0x7fffffff;
26 	if(hx<0x00800000) {
27 	    if(hx==0)
28 		return 0x80000001;	/* ilogb(0) = 0x80000001 */
29 	    else			/* subnormal x */
30 	        for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
31 	    return ix;
32 	}
33 	else if (hx<0x7f800000) return (hx>>23)-127;
34 	else return 0x7fffffff;
35 }
36